People have some strange ideas about electricity. I have an uncle that is convinced it is out to get him. He'll change light bulbs, plug things in and flip switches, but don't let him see any bare wires. And he would have been amazed at the Animal Planet show I saw yesterday in which a dog flipped a light switch with his mouth.
Alright, getting zapped by electricity isn't much fun. I literally stuck my finger in a lightsocket once in my preteens. I concluded that I had learned everything I needed to know from that experience and thus didn't need to repeat it. Likewise it only took one self-administered zapping with a cattle prod to impress me. But early on I noticed the strange sensation you get when you put your tongue across a 9V battery, and it's still a quick and dirty way to see if it still has any life.
If you're careful you can work 120V circuits "hot", but I wouldn't recommend it for everyone. If you're careless when hooking up phone wires it's possible to get 48VDC, which will get your attention. Lesser voltages are no big deal though.
Once at work I was inspecting one of my systems when I got bit when I touched the metal sheath around some calcium silicate insulation and something that was grounded at the same time. A minute or so later I got bit again in a different spot the same way. It felt a bit weaker than a phone zapping, so I told our electricians about it and told them I'd felt about 40V.
To the amusement of the electricians, I was within a volt or two. It turned out that some heat tracing wires (installed to keep pipes warm and thus keep solids from coming out of solution) had been damaged by the metal around the insulation, and this metal was not grounded. That is, until I touched it while I was grounded. I'm lucky the damage wasn't closer to the hot end of the wire.
Enough thrills and chills for one day - my post about grounding and electrical codes will have to wait until later. Try not to get electrocuted in the meantime.